The present invention is related to an optical device, and more particularly to a multi-lenses optical device.
Image processing is often used for photography or movie. As we know, the scanner plays an indispensable role in this field. Increasing the resolution of a scanner is investigated hard in order to get more clear images, but high cost of a scanner with high resolution is not avoidable. The operating principle of the conventional scanner is shown in FIG. 1. An article is placed on the scanner to be scanned. The article is lit by a light source for generating an optical image 11. The optical image 11 of the article is focused on a charge coupled device 13 by a lens set 12, and then is converted to electronic signals to form digital data by the charge coupled device 13. For obtaining a higher resolution, the number of pixels for the charge coupled device 13 must be increased. However, the cost of the charge coupled device 13 is proportional to the square of the number of pixels for it. Requiring higher resolution will thus cost much since the cost of a charge coupled device 13 is a great part of the production cost of a scanner. Frankly speaking, it is difficult to spend lower cost for obtaining higher resolution in the first prior art.
Another method also has been developed to solve the problem of high-cost. Please refer to FIG. 2 showing the operating principle of a scanner according to the second prior art. The optical image of the scanned article is divided into two sections 211 and 212. There are many corresponding lens sets 221 and 222 and corresponding charge coupled devices 231 and 232 for the optical image sections 211 and 212 in this scanner. Different sections 211 and 212 are converted to electronic signals by the same steps as the first prior art by respective lens sets 221 and 222 and charge coupled devices 231 and 232. Finally, the electronic signals will be combined together to form a full image. Hence, the number of pixels for a charge coupled device is reduced, but the performance can be still maintained like that of the prior art. The cost can be reduced by this arrangement. However, the cost is proportional to the number of charge coupled devices. Accordingly, we still hope to make an improvement in increasing resolution and decreasing cost.
An objective of the present invention is to provide a multi-lenses optical device with high resolution, but with less pixels for a photoelectric conversion unit.
In accordance with the present invention, a multi-lenses optical device for converting an initial image to electronic signals includes a plurality of focusing units, a photoelectric conversion unit, a switching unit, and a light-reflecting unit mounted between the photoelectric conversion unit and the plurality of focusing units. The plurality of focusing units are used for focusing a plurality of sections of the initial image respectively, and correspondingly generating a plurality of focused image sections magnified with the same ratio and having different optical path lengths. The photoelectric conversion unit, e.g. charge coupled device, is used for converting the corresponding focused image sections to electronic signals. The switching unit is used for sequentially having each one of the plurality of focused image sections selected and having the selected focused image section transmitted to the photoelectric conversion unit. The light-reflecting unit is used for transmitting the plurality of focused image sections to the photoelectric conversion unit.
In accordance with another aspect of the present invention, the focusing units are lens sets respectively mounted in specific locations for generating the corresponding focused image sections magnified with the same ratio.
In accordance with another aspect of the present invention, the light-reflecting unit preferably includes a first dichroic mirror for transmitting the plurality of focused image sections to the photoelectric conversion unit, and a reflective mirror or a second dichroic mirror for transmitting the plurality of focused image sections from the plurality of focusing units to the first dichroic mirror.
In accordance with another aspect of the present invention, the number of the plurality of focusing units is from 2 to 4.
In accordance with another aspect of the present invention, the switching unit is a light shade set.
In accordance with another aspect of the present invention, the light shade set preferably includes a movable light shade.
In accordance with another aspect of the present invention, the movable light shade may be mounted within the light paths of the plurality of initial image sections for shading the plurality of focusing units from the respective initial image sections except a selected section of the initial image corresponding to the selected focused image section at the instant.
In accordance with another aspect of the present invention, the movable light shade may be mounted between the light-reflecting unit and the plurality of focusing units for shading the light-reflecting unit from the plurality of focused image sections except the selected one generated by a selected focusing unit at the instant.
In accordance with another aspect of the present invention, the movable light shade may be mounted within the light-reflecting unit for shading the photoelectric conversion unit from the plurality of focused image sections except the selected one.
In accordance with another aspect of the present invention, the light shade set preferably includes a rotatable light shade.
In accordance with another aspect of the present invention, the rotatable light shade may be mounted between the light-reflecting unit or within the light-reflecting unit. It is rotated to be in different directions for shading the photoelectric conversion unit from the plurality of focused image sections except the selected one.
The present invention may best be understood through the following description with reference to the accompanying drawings, in which: